opposing the impeachment of a corrupt president in order to weaken the president's party in an upcoming election

There are many reasons why George W Bush deserved to be impeached, his outrageous abuses of power,illegal warrantless wire taps (some of these were U.S. soldiers in Iraq calling home to their families), extraordinary renditions, torturing P.O.W.s etc. In the 2006 election voters soundly rejected the radical Bush agenda, but when Nancy Pelosi became Speaker Of The House she said impeachment was off the table. Keeping Bush in office severely weakened the Republican party and helped the Democrats win the White House and gain seats in Congress in the 2008 election. This is the Pelosi Doctrine.